fix: allow errors to be ignored by links

fix apollographql#6790
fix apollographql#6070

src/core/QueryInfo.ts

@@ -530,9 +530,15 @@ export function shouldWriteResult<T>(
   const ignoreErrors =
     errorPolicy === "ignore" ||
     errorPolicy === "all";
-  let writeWithErrors = !graphQLResultHasError(result);
-  if (!writeWithErrors && ignoreErrors && result.data) {
-    writeWithErrors = true;
+  const hasErrors = graphQLResultHasError(result);
+
+  if (!result.data) {
+    return false;
+  }
+
+  if (hasErrors && !ignoreErrors) {
+    return false;
   }
-  return writeWithErrors;
+
+  return true;
 }

src/core/__tests__/QueryManager/links.ts

@@ -10,7 +10,14 @@ import { itAsync, MockSubscriptionLink } from '../../../testing/core';
 
 // core
 import { QueryManager } from '../../QueryManager';
-import { NextLink, Operation, Reference } from '../../../core';
+import { FetchResult, NextLink, Operation, Reference } from '../../../core';
+import { invariant } from '../../../utilities/globals';
+
+jest.spyOn(invariant, "error");
+
+beforeEach(() => {
+  jest.clearAllMocks();
+})
 
 describe('Link interactions', () => {
   itAsync('includes the cache on the context for eviction links', (resolve, reject) => {
@@ -360,4 +367,50 @@ describe('Link interactions', () => {
         });
       });
   });
+  itAsync('allow errors to be ignored for mutations', (resolve, reject) => {
+    const mutation = gql`
+      mutation UpdateLuke {
+        people_one(id: 1) {
+          name
+          friends {
+            name
+          }
+        }
+      }
+    `;
+
+    const errorLink = (operation: Operation, forward: NextLink) => {
+      const ignoreErrorResult: FetchResult = {
+        data: null,
+        errors: [],
+      }
+
+      return new Observable<FetchResult>(observer => {
+        forward(operation).subscribe({
+          next: observer.next.bind(observer),
+          complete: observer.complete.bind(observer),
+          error() {
+            observer.next(ignoreErrorResult);
+          }
+        })
+      });
+    };
+
+    const mockLink = new MockSubscriptionLink();
+    const link = ApolloLink.from([errorLink, mockLink]);
+    const queryManager = new QueryManager({
+      cache: new InMemoryCache({ addTypename: false }),
+      link,
+    });
+
+    queryManager.mutate({ mutation })
+      .then(() => {
+        expect(invariant.error).not.toBeCalled();
+        resolve();
+      })
+      .catch(reject);
+
+    // fire off error
+    mockLink.simulateResult({ error: new Error("UNAUTHENTICATED") });
+  });
 });

src/react/hooks/__tests__/useMutation.test.tsx

@@ -468,8 +468,7 @@ describe('useMutation Hook', () => {
         });
 
         expect(fetchResult).toEqual({});
-        expect(errorMock).toHaveBeenCalledTimes(1);
-        expect(errorMock.mock.calls[0][0]).toMatch("Missing field");
+        expect(errorMock).not.toBeCalled();
         errorMock.mockRestore();
       });
     });

src/react/hooks/__tests__/useSubscription.test.tsx

@@ -520,10 +520,7 @@ describe('useSubscription Hook', () => {
     await expect(waitForNextUpdate({ timeout: 20 }))
       .rejects.toThrow('Timed out');
 
-    expect(errorSpy).toHaveBeenCalledTimes(1);
-    expect(errorSpy.mock.calls[0][0]).toBe(
-      "Missing field 'car' while writing result {}",
-    );
+    expect(errorSpy).not.toBeCalled();
     errorSpy.mockRestore();
   });
 
@@ -588,16 +585,7 @@ describe('useSubscription Hook', () => {
     await expect(waitForNextUpdate({ timeout: 20 }))
       .rejects.toThrow('Timed out');
 
-    expect(errorSpy).toHaveBeenCalledTimes(3);
-    expect(errorSpy.mock.calls[0][0]).toBe(
-      "Missing field 'car' while writing result {}",
-    );
-    expect(errorSpy.mock.calls[1][0]).toBe(
-      "Missing field 'car' while writing result {}",
-    );
-    expect(errorSpy.mock.calls[2][0]).toBe(
-      "Missing field 'car' while writing result {}",
-    );
+    expect(errorSpy).not.toBeCalled();
     errorSpy.mockRestore();
   });